Add the following to the end of any YouTube video URL, to boost the quality of the video. It helps if the video was shot in HD and uploaded 16x9. &fmt=18
The above is what should follow the youtube URL to make it HD
This is a link to the above video with the HD link already applied. I think it only works with the new beta player. To use it just click the button that is below the rating stars. http://www.youtube.com/watch?v=hD-Uqnisc9c&fmt=18
Make sure that &fmt=18 follows the video's URL.